Effectiveness of bait tubes for brown treesnake control on guam

Abstract

In 2008, we studied simulated toxicant efficacy to control invasive brown treesnakes (Boiga irregularis) using bait tubes (elongate bait stations that reduce non‐target bait take) in a 5‐ha enclosure in Guam (U.S. Territory) with a known population of snakes. Instead of toxicants, we implanted radiotransmitters in small (6.6 ± 1.4 g) and large (21.8 ± 2.9 g) bait‐mouse carcasses, offered from 2 types of bait tubes over a 3‐month period. The known snake population allowed us to characterize not only the snakes taking bait, but also those evading our mock control effort. Tube design had no effect on take rate, but snout–vent length was a strong predictor of bait take: none of the 30 snakes <843 mm in length took any bait, whereas 77 of the 126 snakes ≥843 mm in length took 164 baits. While medium‐sized snakes preferentially ingested small bait (and the largest snakes tended to take large mice more frequently), some of the smallest snakes that took bait ingested large mice. Snake body condition was positively correlated to take rate, but snake sex had no discernible effect. Our data show that there is a relatively narrow size (and, thus, time) gap between the size at which the snakes become susceptible to bait‐mouse take and the size at which they become sexually mature. This has implications for the timing of repeated baiting efforts, if the goal is eradication rather than suppression. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Behavioral differences following ingestion of large meals and consequences for management of a harmful invasive snake: A field experiment

“…The effectiveness of various tools for the capture or lethal control of invasive brown treesnakes depends largely on detectability or targetability; that is, given a quantified level of effort, what is the probability of detecting, capturing, or killing an individual snake within the activity area? Effectiveness of visual surveys, trapping, and toxic bait tools for brown treesnake control has been demonstrated to be influenced by internal factors (sex, size, and body condition) and external factors (availability of alternative prey; Gragg et al., ; Rodda, Savidge, Tyrrell, Christy, & Ellingson, ; Tyrell et al., ; Christy, Yackel Adams, Rodda, Savidge, & Tyrrell, ; Lardner et al., ; Christy, Savidge, Yackel Adams, Gragg, & Rodda, ; Siers, Savidge, & Reed, ). These factors have also been indicated to influence brown treesnake movement characteristics (Santana‐Bendix, ; Tobin, Sugihara, Pochop, & Linnell, ; Siers, Reed, & Savidge, ; Christy et al., ).…”

“…These factors have also been indicated to influence brown treesnake movement characteristics (Santana‐Bendix, ; Tobin, Sugihara, Pochop, & Linnell, ; Siers, Reed, & Savidge, ; Christy et al., ). If brown treesnakes decrease movement and foraging during digestion, this will have implications for the effectiveness of various control tools that typically rely either on visual detection by human searchers or response of foraging snakes to lures or baits (e.g., Christy et al., ; Clark et al., ; Engeman & Vice, ; Lardner et al., ; Tyrell et al., ).…”

Genomic pedigree reconstruction identifies predictors of mating and reproductive success in an invasive vertebrate

“…For example, Tyrrell et al () found a minimal positive effect of BCI on female trappability and a negative effect of BCI on male trappability, such that males with low BCIs were caught in baited traps more often. Differently, Lardner et al () found a positive correlation between BCI and accession of bait tubes for both sexes. Our study demonstrated that BCI has a positive effect on AMS and ARS for males, with a similar effect of BCI on ARS supported for females.…”

Quantile regression of microgeographic variation in population characteristics of an invasive vertebrate predator

“…During growth, Brown Treesnakes undergo a pronounced ontogenetic shift from a diet consisting almost exclusively of ectothermic prey (small lizards) to endotherms (birds and mammals) as adults [7–9]. Because current control technologies rely on rodents as trap or toxicant lures, the strong preference of juvenile snakes for small lizard prey renders these tools largely ineffective against snakes in smaller size classes [10,11]. For this reason, along with a snake’s transition into maturity as it grows [12], snake body size is the individual characteristic of greatest importance with respect to its ecology and management.…”